U.S. Defense Secretary Chuck Hagel is stepping down, according to reports.The New York Times reports he is leaving his post under pressure. President Obama is expected to confirm Hagel’s departure in a news conference from the White House this afternoon.Hagel is the only Republican on Obama’s national security team. The NYT reports he and Obama have mutually agreed on his leaving.Hagel had been brought on to the national security team to oversee military withdrawal in Afghanistan and management of the Pentagon's budget.